# Combine every element with every other element of an object (cross-product)

I have two vectors of integers, say `v1=c(1,2)`

and `v2=c(3,4)`

, I want to combine and obtain this as a result (as a data.frame, or matrix):

> combine(v1,v2) <--- doesn't exist 1 3 1 4 2 3 2 4

This is a basic case. What about a little bit more complicated - combine every row with every other row? E.g. imagine that we have two data.frames or matrices d1, and d2, and we want to combine them to obtain the following result:

d1 1 13 2 11 d2 3 12 4 10 > combine(d1,d2) <--- doesn't exist 1 13 3 12 1 13 4 10 2 11 3 12 2 11 4 10

How could I achieve this?